Single-face and double-face corrugated paperboard containers have been used extensively for packaging since the turn of the century. In the early days the single-face corrugated paperboard was commonly used as bottle wraps, cushioning, dividers and partitions in wood boxes. Single-face board was often used for wrapping glass bottles and sometimes was provided with a facing sheet wider than the corrugated web to provide fly portions extending beyond the opposite ends of the bottle to provide material for closing the ends of the wrapped package.
During the last 80 years, the use of double-face corrugated board for shipping containers has increased to the point where almost every conceivable item of commerce is shipped in containers made of this material. This corrugated board combines great stiffness and rigidity with high cushioning ability and for this reason has been found ideal for most shipping containers. The flutes of the corrugated core are anchored at both sides to the facing sheets thereby forming a continous arch structure which is similar to the truss structure of a bridge and has tremendous strength. It has been estimated that ninety percent or more of the shipping boxes moving by rail freight are made of double-face corrugated material.
Single-face corrugated board, on the other hand, lacks the strength and rigidity required for shipping boxes and is used principally for wrapping and interior packing. As a result the use of single-face corrugated board has been very limited. It has been estimated that single-face represents only about two percent of all manufactured corrugated board.
For many decades corrugated board has been preferred for a vast majority of shipping containers because of its low cost compared to other materials. The manufacture of single-face and double-face corruguated board is very economical because the board can be made in a continous process using automatic machines capable of operation at very high speeds, sometimes 600 feet per minute or higher. Because of its low cost, it has been difficult to improve upon standard double-faced corrugated board as a material for most shipping containers.
During the last twenty years the manufacturers of the double-face corrugated board have produced improved forms of board wherein the ends of the flutes or corrugations are closed or reinforced by bending or deforming one or both of the facing sheets at the side edges of the board. Various forms of double-faced corrugated board with wrapped or reinforced side edges are disclosed in the following U.S. Pat. Nos. 3,031,256; 3,307,995; 3,399,096; 3,432,375; 3,563,843; 3,579,396; 3,624,236; 3,711,352; and 3,785,908. While these special types of double-faced corrugated boards have certain advantages, their use has been limited because of the added cost of manufacture.